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The Single UNIX &reg; Specification, Version 2<br>
Copyright &copy; 1997 The Open Group

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<h4><a name = "tag_000_001_086">&nbsp;</a>NAME</h4><blockquote>
acosh, asinh, atanh - inverse hyperbolic functions
</blockquote><h4><a name = "tag_000_001_087">&nbsp;</a>SYNOPSIS</h4><blockquote>
<pre><code>

#include &lt;<a href="math.h.html">math.h</a>&gt;

double acosh(double <i>x</i>);
double asinh(double <i>x</i>);
double atanh(double <i>x</i>);
</code>
</pre>
</blockquote><h4><a name = "tag_000_001_088">&nbsp;</a>DESCRIPTION</h4><blockquote>
The
<i>acosh()</i>,
<i>asinh()</i>
and
<i>atanh()</i>
functions compute the inverse hyperbolic cosine, sine, and tangent of their
argument, respectively.
</blockquote><h4><a name = "tag_000_001_089">&nbsp;</a>RETURN VALUE</h4><blockquote>
The
<i>acosh()</i>,
<i>asinh()</i>
and
<i>atanh()</i>
functions return the inverse hyperbolic cosine, sine, and tangent of their
argument, respectively.
<p>
The
<i>acosh()</i>
function returns an implementation-dependent value (NaN or equivalent if
available) and sets
<i>errno</i>
to [EDOM] when its argument is less than 1.0.
<p>
The
<i>atanh()</i>
function returns an implementation-dependent value (NaN or equivalent if
available) and sets
<i>errno</i>
to [EDOM] when its argument has absolute value greater than 1.0.
<p>
If
<i>x</i>
is NaN, the
<i>asinh()</i>,
<i>acosh()</i>
and
<i>atanh()</i>
functions return NaN and may set
<i>errno</i>
to [EDOM].
</blockquote><h4><a name = "tag_000_001_090">&nbsp;</a>ERRORS</h4><blockquote>
The
<i>acosh()</i>
function will fail if:
<dl compact>

<dt>[EDOM]<dd>The <i>x</i> argument is less than 1.0.

</dl>
<p>
The
<i>atanh()</i>
function will fail if:
<dl compact>

<dt>[EDOM]<dd>The <i>x</i> argument has an absolute value greater than 1.0.

</dl>
<p>
The
<i>atanh()</i>
function will fail if:
<dl compact>

<dt>[ERANGE]<dd>
The <i>x</i> argument has an absolute value equal to 1.0

</dl>
<p>
The
<i>asinh()</i>,
<i>acosh()</i>
and
<i>atanh()</i>
functions may fail if:
<dl compact>

<dt>[EDOM]<dd>The value of <i>x</i> is NaN.

</dl>
</blockquote><h4><a name = "tag_000_001_091">&nbsp;</a>EXAMPLES</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_001_092">&nbsp;</a>APPLICATION USAGE</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_001_093">&nbsp;</a>FUTURE DIRECTIONS</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_001_094">&nbsp;</a>SEE ALSO</h4><blockquote>
<i><a href="cosh.html">cosh()</a></i>,
<i><a href="sinh.html">sinh()</a></i>,
<i><a href="tanh.html">tanh()</a></i>,
<i><a href="math.h.html">&lt;math.h&gt;</a></i>.
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UNIX &reg; is a registered Trademark of The Open Group.<br>
Copyright &copy; 1997 The Open Group
<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]

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